135 Opti "missing" at WOT

[Trapper]

My 1998 135 Opti is missing (slight hesitation) at WOT. The plugs are non-platinum and were changed a couple years ago. My thoughts are that I need to replace the plugs and I will replace with the platinums. I am also wondering if it could be the air or fuel filter which were both replaced last year. I run this motor a lot and have not had any problems so I am hoping this is an easy fix as well. Any other ideas? Thanks.

[Furball]

I have a 1999 150 Opti that started missing once in a while last year. I talked to the mechanic where I bought it from and he said to check the battery connections as the Opti is very voltage sensitive. I cleaned everything up and hasn't missed since.